The present invention refers to a dispenser for pasty compositions, having a housing containing a piston which is displaceable only in the emptying direction and an actuating handle on the outside which is developed on a head piece which can be compressed bellows-like in the direction towards the piston, said head piece having a dispenser outlet opening from which there extends, directed inwards, a small tube, the inner mouth-end of which extends freely into the pasty composition in every position of the bellows.
A dispenser of this kind is known from Federal Republic of Germany OS 30 42 285. The pasty composition present in the small tube exerts a valve function. The pulling of the piston over the column of filling material is effected by way of priority, i.e. before the residual amount in the small tube which acts in blocking fashion and in plug-like manner could compensate for the existing vacuum by air. The blocking of the piston in the other direction is effected by use of a so-called clamping module. The latter is placed on the wide surface of the piston facing the stand-side end of the housing; it is a multi-pointed star-shaped structural part of spring steel. The diameter circumscribing the ends of the points is greater than the inside diameter of the housing so that the ends of the points hook themselves as oblique supporting feet on the inner wall of the housing. Such a structural part is relatively expensive for a throw-away mass-produced article. Also an additional mounting step results. In addition to this, relatively high frictional forces must be overcome, as a result of which certain limits are established with respect to the viscosity.
The object of the present invention is so to develop a dispenser of this type in a form which is simple to manufacture and stable in use that the one-sided displacement of the piston is effected without structural parts on the piston.